This invention relates to a method of inspecting and working V-shaped grooves, for example, those as formed in a substrate of an optical fiber connector with high accuracy of the order of submicrons.
In order to accurately connect optical fibers having a diameter of approximately 100 .mu.m whose center axes are aligned with each other, connectors have been developed in which the optical fibers are embraced between a pair of chips formed in their surfaces with V-shaped grooves.
Such chips are made of a hard material such as ceramics, glass ceramics and quenched steel. The V-shaped grooves are formed by means of a rotating grinding wheel having a sharpened periphery edge. As any worked errors in the worked V-shaped grooves will directly cause deflections of axes or the optical fibers, the V-shaped grooves must be inspected to ensure high accuracy.
However, as the V-shaped grooves are on the order of 100 .mu.m depth and 150 .mu.m width, the measurement of surface roughness determined in ISO is not applicable to the inspection of the grooves. Even if a surface roughness tester is used, significant measured values can not be obtained.
In order to solve this problem, the following method has been proposed. In this method, as shown in FIG. 1, a master gauge 2 having a diameter equal to those of optical fibers to be used is arranged in a V-shaped groove 1 and a height of the master gauge 2 is measured by means of a stylus 3. A position and accuracy of the optical fiber in an actually used state are presumed with the aid of the measured value.
With this method, however, the accuracy is likely to be detrimentally affected by an unreliable master gauge, scores or scratches and locational conditions of the master gauge. Therefore, it is quite impossible to measure pitches of V-shaped grooves with an accuracy greater than 1.0 .mu.m.
As shown in FIG. 2, moreover, a method has been proposed in which a V-shaped groove itself is directly measured with a stylus 3 to inspect whether a depth, width, pitch and the like are within allowable tolerances. In this method, however, errors occur due to chipping, breaking off, caulking and the like at edges of the V-shaped grooves. In addition, it is impossible with this method to accurately detect partial changes in angle .theta. of the V-shaped groove due to wear of tips of a grinding wheel.